Sum of array elements excluding the elements which lie between a and b

Given an array of N unique numbers. Also given two numbers a and b such that a will always be before b in the array. The task is to find the sum of the array elements excluding the elements which lie between a and b.

Examples:

Input : arr = [2, 1, 6, 9, 11], a = 6, b = 9 
Output : 14

Input : arr = [1, 2, 4, 5, 6], a = 2, b = 5 
Output : 7

Approach: Traverse in the array, keep adding the array elements until we find a. Continue iteration until b is found and do not add array elements to the sum. After b is found, add array elements to the sum till the end. Once the iteration is completed, return the sum.

Below is the implementation of the above approach: 

C++

// CPP implementation of above approach
#include <bits/stdc++.h>
using namespace std;

// Function to find sum
// of array excluding the
// range which has [a, b]
void sumexcludingrange(vector<int> li, int a, int b)
{
    int sum = 0;
    bool add = true;

    // loop in li
    int n = li.size();
    for (int i = 0; i < n; i++) {

        // if no != a then add
        if (li[i] != a && add == true)
            sum = sum + li[i];

        // mark when a
        // and b are found
        else if (li[i] == a)
            add = false;
        else if (li[i] == b)
            add = true;
    }

    // print sum
    cout << (sum);
}

// Driver Code
int main()
{
    vector<int> lis{ 1, 2, 4, 5, 6 };
    int a = 2;
    int b = 5;

    sumexcludingrange(lis, a, b);
}
// This code is contributed by
// Sahil_Shelangia

Java

// Java implementation of above approach

// Function to find sum
// of array excluding the
// range which has [a, b]
import java.io.*;

class GFG {
    static void sumexcludingrange(int li[], int a, int b)
    {
        int sum = 0;
        boolean add = true;

        // loop in li
        for (int i = 0; i < li.length; i++) {

            // if no != a then add
            if (li[i] != a && add == true)
                sum = sum + li[i];

            // mark when a
            // and b are found
            else if (li[i] == a)
                add = false;
            else if (li[i] == b)
                add = true;
        }

        // print sum
        System.out.print(sum);
    }

    // Driver Code
    public static void main(String[] args)
    {
        int lis[] = { 1, 2, 4, 5, 6 };
        int a = 2;
        int b = 5;

        sumexcludingrange(lis, a, b);
    }
}

// This code is contributed
// by anuj_67.

Python3

# Python3 implementation of above approach

# Function to find sum
# of array excluding the
# range which has [a, b]


def sumexcludingrange(li, a, b):

    sum = 0
    add = True

    # loop in li
    for no in li:

         # if no != a then add
        if no != a and add == True:
            sum = sum + no

        # mark when a and b are found
        elif no == a:
            add = False
        elif no == b:
            add = True

    # print sum
    print(sum)


lis = [1, 2, 4, 5, 6]
a = 2
b = 5

sumexcludingrange(lis, a, b)

C#

// C# implementation of above approach

// Function to find sum
// of array excluding the
// range which has [a, b]

using System;

class GFG {
    static void sumexcludingrange(int[] li, int a, int b)
    {
        int sum = 0;
        bool add = true;

        // loop in li
        for (int i = 0; i < li.Length; i++) {

            // if no != a then add
            if (li[i] != a && add == true)
                sum = sum + li[i];

            // mark when a
            // and b are found
            else if (li[i] == a)
                add = false;
            else if (li[i] == b)
                add = true;
        }

        // print sum
        Console.Write(sum);
    }

    // Driver Code
    public static void Main()
    {
        int[] lis = { 1, 2, 4, 5, 6 };
        int a = 2;
        int b = 5;

        sumexcludingrange(lis, a, b);
    }
}

Javascript

<script>

// JavaScript implementation of above approach

// Function to find sum
// of array excluding the
// range which has [a, b]
function sumexcludingrange(li, a, b)
{
    let sum = 0;
    let add = true;

    // Loop in li
    for(let i = 0; i < li.length; i++)
    {

        // If no != a then add
        if (li[i] != a &&
              add == true)
            sum = sum + li[i];

        // Mark when a
        // and b are found
        else if (li[i] == a)
            add = false;
        else if (li[i] == b)
            add = true;
    }

    // Print sum
    document.write(sum);
}

// Driver Code
let lis = [ 1, 2, 4, 5, 6 ];
let a = 2;
let b = 5;

sumexcludingrange(lis, a, b);

// This code is contributed by sravan kumar

</script>

Output

7

Time complexity: O(n)
Auxiliary space: O(1)